Southeastern railway and its cleaning firm have been fined a total of £3.6m for the death of a cleaner who was electrocuted by a live rail.

Roger Lower, 46, fell on to the 750-volt rail during a night shift cleaning trains at one of Southeastern’s Sussex depots, where equipment designed to protect workers was found not to be in use.

The father of two from Hastings was found by colleagues lying on the rail. Emergency services were called but were unable to save him.

Southeastern’s owner, London and South Eastern Railways, and its contractor, Wettons Cleaning Services, were fined £2.5m and £1.1m respectively at Guildford crown court on Friday.

The firms were earlier found guilty of breaches of the Health and Safety at Work Act, in a prosecution brought by the rail regulator, the Office of Rail and Road. The ORR inspectors found there was a culture of cutting corners, exposing workers to serious risks.

Lower had worked for Wettons for three months before his death at Southeastern’s West Marina Depot in St Leonards-on-Sea on 24 May 2014. Protection boards to keep workers from the live rail were not in use, inspectors found, with all four available leant up against buffers.

Colleagues of Lower said they were not trained to use the equipment, and had concerns about his safety while cleaning the outside of the train.

An ORR investigation found health and safety failures by both Southeastern and Wettons. It accused the firms of relying on paperwork, and of failing to check on working practices and adequately train and supervise workers.

Ian Prosser, the HM chief inspector of railways, said: “The failings by Wettons and Southeastern were unacceptable and show the consequences of not abiding by health and safety, including the provisions of the law. As always, ORR is committed to monitoring compliance and taking tough enforcement action when necessary, as this tragic case demonstrates.”

Southeastern said it commissioned an independent review after the incident and introduced additional safety checks and equipment. David Statham, its managing director, said: “We deeply regret that we did not prevent the death of Roger Lower. At Southeastern, we set ourselves high safety standards underpinned by robust procedures. We recognise that on this occasion there’s more we and our contractors could have done to meet those high standards.”